Cracking the Code: Understanding the Difference Between UPF and SPF

What is the difference between UPF and SPF? UPF stands for Ultraviolet Protection Factor and refers to the sun protection offered by hats, shirts, sleeves, and pants. UPF ratings are based on laboratory testing of the fabric and the amount of UV radiation that passes through it. The higher the number, the more protection. For example, a UPF 50+ rating only lets 2% of the damaging UV rays through—meaning your skin would be protected from sunburns and long-term damage, even when you’re covered up.

Unlike sunscreen, which has to be applied and then reapplied regularly, UPF-rated clothing is designed with sun protection built in. The specialized fabrics and treatments help prevent the sun’s harmful rays from reaching your skin, which can cause various issues, including rashes, wrinkles, and cancers. The fabric’s construction and color also play a role in its UPF rating, with thicker fabrics like denim or wool typically scoring higher than lighter ones. Moisture can also reduce a garment’s UPF rating, so many brands add moisture-wicking features to their designs.

The SPF on sunscreen tells you how long it might take to get sunburned by the UVB rays that cause sunburn and skin cancer. SPF ratings are based on indoor experiments that expose people to varying levels of UV radiation and then record how many seconds it takes them to redden.

When going out in the sun, it’s recommended by most dermatologists to use an SPF of 30 or higher. It’s important to note that while SPF protects against UVB rays, it doesn’t protect against UVA rays, which can cause age-related skin damage and other health issues as they penetrate deeper into the skin.

Two primary ways to protect your skin from UV rays are sunscreen and UPF clothing. While sunscreens rely on chemicals to block UV radiation, UPF clothing is designed using various weaving methods and dyes that physically impede the rays from reaching the skin.

Our sunscreens have chemicals that keep UV rays from penetrating and damaging the skin. UPF fabrics, on the other hand, use “various weaving methods, dyes and photo-protecting chemicals to impede UV radiation from passing through and reaching your skin,” says the outdoor retailer.

Laboratories gauge the UPF rating of fabric by comparing how much UV reaches the skin through its fibers while considering factors like moisture and how tight or loose the material is. However, it is essential to note that sunscreen and clothing are only effective if you wear them properly and regularly.

Also, if you’re taking certain medications that increase sun sensitivity — such as some antihistamines and antibiotics — it is essential to apply sunscreen correctly and often and cover up when possible. And don’t forget a broad-rimmed hat and sunglasses. They can provide additional protection for the face, neck, ears, and scalp, Dr. Shainhouse adds.

UPF ratings directly measure a fabric’s ability to block UV radiation. The material may be dark-colored, densely woven, or contain photo-protective chemicals. A shirt with a UPF rating 50 allows less than 1/50th of the sun’s rays to reach your skin.

Previously, clothing was rated using SPF standards that measured how long you could stay in the sun before your skin reddens. These SPF numbers don’t consider UVA rays that penetrate deeper into your skin and can cause premature aging and skin cancer.

A UPF-rated garment, like our rash vests and hats, is much better than a regular cotton t-shirt because it offers more protection. However, it’s still important to apply sunscreen and reapply it often. And remember to schedule your routine skin checks and book your appointment.